A positive cranial drawer test means the tibia can move cranially when the femur is in a fixed position [ 2, 6 ]. The movement of the unstable stifle joint and ruptured CCL can be very painful for the patient, so this test should be carried out under sedation or general anaesthesia, when necessary. However, this patient did not show signs of pain when conscious during the examination, so the VS carried out the test during the initial consultation.
Following the diagnosis of a CCL rupture, the patient was admitted to the hospital for sedation to radiograph the stifle joint and a general anaesthetic to perform tibial plateau levelling osteotomy( TPLO) surgery on the right stifle, along with further treatment as necessary. Once the patient was hospitalised, the VS prescribed sedation of 10 µ g / kg medetomidine and 0.2 mg / kg butorphanol, which was administered intravenously. This provided adequate sedation for radiographs of both stifles to be taken( Figure 3).
Figure 3a. Preoperative radiograph of the patient ' s right stifle.
Figure 3b. Preoperative radiograph of the patient ' s right stifle.
These radiographs were used for surgical planning, and surgery was scheduled the following day. It was confirmed that TPLO surgery would be the most appropriate surgical procedure for this patient.
Surgery considerations
There are many surgical techniques that can be used to repair a ruptured CCL. These are split into two categories: osteotomy techniques and suture techniques. The VS should take into consideration the patient ' s anatomy, lifestyle, physiology and age when planning treatment.
Surgical repair of the CCL is the only way to resolve stifle instability; however, not all patients are surgical candidates, so non-surgical treatment may be advised. This can include restricting activity, long-term analgesia, joint supplements, or custom knee braces or orthotics [ 4 ]. All viable options and the associated risks for the patient should be discussed with the owners so they can make an informed decision.
TPLO surgery is an osteotomy technique that requires a bone to be cut, to change how the quadriceps muscles act on the tibial plateau. The cut bone is then stabilised by the placement of a bone plate and screws. Stability of the ruptured CCL is achieved by changing the biomechanics of the stifle joint rather than by replacing the CCL. This technique has a better outcome compared with other techniques, but complications are possible [ 4 ]. The bone has to heal following an osteotomy and any problems associated with this could lead to multiple corrective surgeries and a poor outcome for the patient [ 4 ].
Preoperative assessment and care
When formulating a general anaesthetic plan with an anaesthetist, a preoperative assessment is performed to assess the patient ' s physiological parameters( Table 1 [ 7 – 9 ]). This should occur 12 – 24 hours before the general anaesthetic is scheduled to happen.
Table 1. The patient ' s preoperative assessment.
Parameter Patient measurement Normal range for large-breed dogs [ 7 – 9 ] Heart rate 85 bpm 60 – 120 bpm Respiratory rate 20 breaths / min 18 – 34 breaths / min Temperature 38.5 ° C 37.5 – 39.2 ° C Mucous membranes Pink and moist, CRT < 2 seconds Pink and moist, CRT 1 – 2 seconds Heart and lung auscultation Nothing abnormal detected No abnormalities Body condition 5 / 9 * 4 – 5 / 9 Mentation Bright, alert and responsive Bright, alert and responsive Behavioural assessment Nervous but friendly N / A
bpm, breaths per minute; CRT, capillary refill time; N / A, not applicable. * This score suggests the patient ' s bodyweight is ideal [ 9 ].
50 Veterinary Nursing Journal